The present invention is a zero insertion force percutaneous connector and a flexible brain probe assembly.
Fitting a probe assembly for measuring electrical activity of a mammalian test subject or patient""s brain is a challenging operation. A problem is encountered in fitting the subject with a percutaneous connector assembly (a connector assembly having an in vivo connector half that extends through the skin) that does not unduly cause pain or creates a risk of infection. Complicating this task is the necessity of passing many different signal conductors through the percutaneous connector, a requirement that has significantly increased the size of the typical percutaneous connector.
Also, the in vivo connector half generally mates with an ex vivo connector half that routs the signals created by the connector to a destination, such as a piece of test equipment. Each time this cable is connected, some force must typically be applied to create the connection. As the site of the percutaneous connector may be quite tender, this generally causes pain or pressure to the subject. In a separate consideration, it is highly desirable to amplify the signals produced by the brain as closely as possible to the signal origin.
Creating the probe that contacts the brain tissue also represents a challenge to researchers. Researchers typically wish to measure electrical activity at specific sites within the brain that share a well-defined physical relationship to one another. Probes produced by photolithographic techniques, such as the probe designed by personnel at the University of Michigan that is known in the industry and research community as the xe2x80x9cUniversity of Michigan Probe,xe2x80x9d permit the accurate placement of electrode sites that are sufficiently small to permit the measurement of electrical activity at a specific set of predefined sites within the brain. Unfortunately, the desire to use photolithography has prompted the use of silicon as a substrate. Because this material is quite brittle, the use of it creates a risk of breakage inside the brain, endangering the subject or patient and limiting the insertion strategies available to researchers. Moreover, the use of silicon prevents the University of Michigan probe from moving with the brain, which does move about slightly within the skull. In addition, silicon is subject to some restoring force, which tends to cause a silicon probe to migrate over time. Both of these drawbacks have the potential result of causing trauma to the brain tissue.
Another type of probe that is currently available includes a set of insulated wires having laser created apertures exposing electrode sites. Although this type of probe is useful for many applications, it does not yield the precision or the freedom of electrode placement that the University of Michigan probe permits.
What is needed but not yet available is an electrode probe and method of making the same that affords unconstrained and accurate placement of the electrodes, but offers flexibility and robustness and is thereby less susceptible to breakage than currently available probes.
Also needed but not yet available is a percutaneous connector wherein the male-half can be inserted into the female-half without exerting pressure against the female-half, thereby avoiding the pain and/or tissue trauma that the insertion operation currently causes to patients and test subjects. In addition, a percutaneous connector is needed that brings a set of op-amps closer to the site where the signals exit the body than has heretofore been possible.
In a first separate aspect, the present invention is a percutaneous connector. It comprises a female-half including a housing having a pair of side walls, each having an interior surface. An electrical contact assembly is arranged along the interior surface of at least one of the side walls and has a set of first electrical contacts. Insulating material electrically isolates the electrical contacts from one another. In addition, an electrical conductor attached to each electrical contact extends outside of the housing. A male-half includes a sheet of resilient material, bent into a U-shape and having two opposed outer surfaces. A handle assembly is adapted to permit a user to squeeze the two opposed outer surfaces closer to each other. In addition a set of second contacts is attached to at least one of the outer surfaces and is arranged in matching configuration to the first set of contacts. Insulating material electrically isolates the contacts from one another. With this design, a user can grasp the male-half by the handle assembly, squeeze together the two outer surfaces, place the male-half in the female-half and release the handle assembly so that the male set of contacts touches the female set of contacts.
In a second separate aspect, the present invention is a connector assembly for connecting a set of first conductors to a set of second conductors that includes a first half and a second half that mates to the first half. The first half includes a substrate of resiliently compressible, insulating material, which supports a set of first contacts, each connected to a the first conductor. In addition, the substrate of resiliently compressible, insulating material defines a set of isolation cuts, each disposed about one of the first contacts and detaching the substrate of resiliently compressible, insulating material inside of the isolation cut from the substrate of material outside of the isolation cut. The second half of the connector assembly comprises an insulating substrate and a set of second contacts, each connected to the second conductor and supported by the insulating substrate, and positioned in matching arrangement to the set of first contacts. A connective bracket assembly is adapted to hold the first set of contacts in contact to the second set of contacts.
In a third additional separate aspect, the present invention is a method of producing an electrode probe assembly, comprising, providing a flexible polymer substrate bearing a coating of conductive material and using photolithography and electroplating to form a set of contacts and conductors on the flexible polymer substrate.
In a fourth additional separate aspect, the present invention is a percutaneous connector comprising a first half and a mating second half. The first half is adapted to be set into the body of a patient and includes an array of first contacts having a density of greater than 25 contacts per cm2. The second half is adapted to mate with the first half and includes an array of second contacts positioned in mating conformity with the set of first contacts and further including a set of op-amps, each connected to one of the second contacts and positioned within 2 cm that second contact.
The foregoing and other objectives, features and advantages of the invention will be more readily understood upon consideration of the following detailed description of the preferred embodiment(s), taken in conjunction with the accompanying drawings.